The digestion of pizza, the light reactions in photosynthesis, and the removal of a stain by laundry detergent all require ENZYMES, which are biological proteins that lower the activation energy for chemical reactions.

A student examines a cell under the microscope and determines that it is a eukaryote. All but one structure could help the student come to this conclusion. The structure that is of no help is the CELL WALL, because this could denote either a prokaryote or a eukaryote.